1,720,978 research outputs found
A new adaptive approach for on-line parameter and state estimation of induction motor
No full textA novel adaptive observer is proposed to perform on-line estimation of both state and parameters of the electrical part of
induction motors. The rotor mechanical speed and the stator currents/voltages are assumed to be measured. A particular nonminimal state representation of the machine electrical model is derived and exploited to build the adaptive observer, based on a
series–parallel architecture. Lyapunov design is used to develop the adaptation law of the proposed solution. Both simulation results
and experimental tests confirm the good performances of the technique
DEIS UAV: GNC Design and avionics implementation issues.
No full textGuidance Navigation and Control (GNC) system of an Unmanned Aerial Vehicle (UAV). The vehicle, thanks to a partially autonomous flight capability, aims to be a very low cost and compact solution to perform significant flight test of general GNC algorithms or as a platform for mission oriented experiments, compared to very
expensive aircraft based flight tests. The development activity includes the project, the synthesis and the assembly of the on–board avionics equipment, together with the software implementation for data collection and some basic GNC algorithms. A
demonstrative application will be the test of some integrity monitoring functions and algorithms with the use of data collected during some flight
Fault Detection and Isolation for On-Board Sensors of a General Aviation Aircraft
No full textThis paper addresses the problem of the detection and isolation of the input and output sensor faults on a
general aviation aircraft, which is characterized by a non-linear model, in the presence of wind gusts,
atmospheric turbulence and measurement errors. In particular, this work proposes a polynomial approach
for the design of residual generators in order to realize complete diagnosis schemes when additive faults are
present. In fact, the use of an input-output description for the linearized model of the aircraft allows to
compute in a straightforward way the residual generators. This approach leads to dynamic filters that can
achieve both good disturbance signal decoupling and robustness properties with respect to both
linearization error and measurement noise. Mathematical descriptions of the aircraft measurement sensors
are also taken into account. The results obtained in the simulation of the faulty behaviour of a PIPER
PA30 aircraft and a comparison with other FDI approaches (both linear and non-linear) are finally
reported
Satellite Navigation Systems
No full textThis chapter describes the Global Navigation Satellite Systems (GNSS) used for positioning and navigation applications. Although a satellite navigation system is very complex, it is common to speak of a “satellite navigation system sensor” when referring to the tools that an end user needs in order to exploit the functionalities of a satellite navigation system, and this chapter will give a general survey of this topic. Firstly, the positioning problem within the framework of a positioning satellite system will be described. Then, general GNSS descriptions and prospects will be presented, outlining the main features of the American GPS – GNSS “gold standard”; the Russian GLONASS (revived and modernized a few years ago); the European Galileo and the Chinese Bei Dou (formerly called Compass), both successfully developing; along with the Japanese QZSS and the Indian IRNSS regional navigation satellite systems. Following these will be sections that include sources of errors and receiver structures common to all GNSS. Modernization and augmentation (GBAS and SBAS) of satellite systems are treated in a specific paragraph. Finally, some brief outlines of the aerospace applications of satellite systems will conclude the chapter.
Major attention has been paid to the principles of satellite positioning, to descriptions of the measurements that can be obtained from satellite signals, the way they are processed, the effects that affect the measurements and how they propagate. These choices were motivated by the fact that their principles are common to all the GNSS and can provide the reader with the tools to approach the following subject matter. Many references are also given in the bibliography for the study of particular topics in depth, but the most recent novelties are quickly outlined because the relevant research is still ongoing and new applications are emerging
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
